U.S. patent number 7,480,306 [Application Number 10/742,653] was granted by the patent office on 2009-01-20 for interworking functionality.
This patent grant is currently assigned to Nortel Networks Limited. Invention is credited to Vasile Radoaca, Paul Unbehagen.
United States Patent |
7,480,306 |
Unbehagen , et al. |
January 20, 2009 |
Interworking functionality
Abstract
In one aspect a system and method for providing communication
between Ethernet and frame relay routers includes generating a
unique media access control (MAC) address for a frame relay router
in communication with an Ethernet router, associating the MAC
address with the frame relay router, and storing the MAC address in
an interworking function device (IWF). The method also includes
receiving at the IWF device an address resolution protocol (ARP)
request from the Ethernet router and sending from the IWF device to
the Ethernet router a response to the ARP request based on the
stored MAC addresses.
Inventors: |
Unbehagen; Paul (Cary, NC),
Radoaca; Vasile (Burlington, MA) |
Assignee: |
Nortel Networks Limited (St.
Laurent, Quebec, CA)
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Family
ID: |
34794631 |
Appl.
No.: |
10/742,653 |
Filed: |
December 19, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050165961 A1 |
Jul 28, 2005 |
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Current U.S.
Class: |
370/401; 370/389;
370/469; 370/475 |
Current CPC
Class: |
H04L
29/12009 (20130101); H04L 29/12018 (20130101); H04L
29/12207 (20130101); H04L 29/12839 (20130101); H04L
61/10 (20130101); H04L 61/20 (20130101); H04L
61/6022 (20130101) |
Current International
Class: |
H04L
12/28 (20060101) |
Field of
Search: |
;370/389-395.1,401-405,351,409,469,475 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Shah, H. et al. "ARP Mediation for IP Interworking of Layer 2 VPN",
PPVPN Working Group Internet Draft, (Versions 00 01 02) (Jun.
2003). cited by other .
Shah, H. et al. "ARP Mediation for IP Interworking of Layer 2 VPN",
PPVPN Working Group Internet Draft, pp. 1-11, (Versions 00 01 02)
(Jun. 2003). cited by other.
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Primary Examiner: Chan; Wing F.
Assistant Examiner: Mais; Mark A.
Attorney, Agent or Firm: Christopher & Weisberg,
P.A.
Claims
What is claimed is:
1. A method for providing communication between an Ethernet router
and a second router having another protocol, the method comprising:
generating a unique media access control (MAC) address for a port
corresponding to the second router in communication with the
Ethernet router; associating the MAC address with the port
corresponding to the second router; storing the MAC address in an
interworking function (IWF) device; receiving an address resolution
protocol (ARP) request from the Ethernet router; and sending to the
Ethernet router a response to the ARP request based on the stored
MAC address.
2. The method of claim 1 further comprising forwarding a packet to
the second router from the Ethernet router based on the response
from the IWF device.
3. The method of claim 1 further comprising sending an inverse
address resolution protocol request upon an addition of a new
router.
4. The method of claim 1 wherein the second router is a frame relay
router.
5. The method of claim 1 the second router is an ATM router.
6. The method of claim 1 wherein the IWF device includes a virtual
socket interface connected to the Ethernet router, wherein the
virtual socket interface reads the MAC address.
7. A system comprising: an input port for a connection to a
corresponding frame relay router, an input for a connection to an
Ethernet router, and control circuitry that is adapted to: generate
a unique media access control (MAC) address for the port
corresponding to the frame relay router; associate the MAC address
with the port corresponding to the frame relay router; store the
MAC address in an interworking function (IWF) device; receive an
address resolution protocol (ARP) request from the Ethernet router;
and send to the Ethernet router a response to the ARP request based
on the stored MAC address.
8. The system of claim 7 further configured to respond to APR
requests based on the MAC address.
9. A method comprising: sending an ARP request from an Ethernet
router; receiving a response to the request from an interworking
function device, the response based on a MAC address for a port
corresponding to a frame relay router stored in the interworking
function device; and forwarding the packet to a frame relay router
using another protocol based on the response.
10. The method of claim 9 further comprising: generating a unique
media access control (MAC) address for the port corresponding to
the frame relay router connected to the Ethernet router; and
associating the MAC address with the port corresponding to the
frame relay router.
11. The method of claim 9 further comprising sending an inverse
address resolution protocol request upon the addition of a new
router.
12. A computer program product, encoded in a computer readable
medium, for executing instructions on a processor, the computer
program product being operable to cause a machine to: generate a
unique media access control (MAC) address for a port corresponding
to a second router in communication with an Ethernet router;
associate the MAC address with the port corresponding to the second
router; store the MAC address in an interworking function (IWF)
device; receive an address resolution protocol (ARP) request from
the Ethernet router; and send to the Ethernet router a response to
the ARP request based on the stored MAC address.
13. The method of claim 12 further comprising forwarding a packet
to the second router from the Ethernet router based on the
response.
14. The method of claim 12 further comprising sending an inverse
address resolution protocol request upon the addition of a new
router.
Description
BACKGROUND
Ethernet and frame relay networks operate using different standards
and protocols. Ethernet is a local area technology, in which
devices attach to a common medium that provides a path along which
the signals will travel. Frame relay networks are based on
packet-switching technology. In order for an Ethernet network to
communicate with a frame relay network an intermediate device
(e.g., a device to encapsulate a package) is needed. Encapsulation
is the inclusion of one data structure within another structure so
that the first data structure is hidden and the network views the
encapsulated packet to forward in the system. For example, an
Ethernet formatted data packet can be encapsulated within
asynchronous transfer mode (ATM) cells to allow packets to be
forwarded from an Ethernet network to an ATM network.
SUMMARY
In one aspect a system and method provides communication between
Ethernet and a second router having another protocol. The system
and method includes generating a unique media access control (MAC)
address for the second router in communication with an Ethernet
router, associating the MAC address with the second router, and
storing the MAC address. The system and method also includes
receiving an address resolution protocol (ARP) request from the
Ethernet router; and sending to the Ethernet router a response to
the ARP request based on the stored MAC addresses.
Embodiments can include one or more of the following. The second
router is a frame relay router or an ATM router. The method can
include forwarding a packet to the frame relay router from the
Ethernet router based on the response from the IWF device.
The method can include sending an inverse address resolution
protocol request upon an addition of a new frame relay router. The
interworking function device can provide a transparent proxy
between the Ethernet router and the frame relay router. The method
can include having a virtual socket interface connected to the
Ethernet router. The virtual socket interface can be included in
the interworking function device and can read the virtual MAC
addresses of the frame relay routers.
In another aspect, a system includes a connection to one or more
frame relay routers and a connection to an Ethernet router. The
system also includes a memory that includes a virtual MAC address
for the one or more frame relay routers in communication with the
Ethernet router, the device configured to enable the Ethernet
router to send data to the frame relay router based on the virtual
MAC address.
Embodiments can include one or more of the following. The system
can be configured to receive ARP requests from the Ethernet router.
The system can be configured to respond to APR requests based on
the virtual MAC addresses.
In another aspect, a method includes sending an ARP request from an
Ethernet router and receiving a response to the request from an
interworking function device. The response is based on a MAC
address for a frame relay router stored in the interworking
function device. The method also includes forwarding the packet to
the frame relay router based on the response.
Embodiments can include one or more of the following. The method
can also include generating a unique media access control (MAC)
address for the frame relay router connected to the Ethernet router
and associating the MAC address with the frame relay router. The
method can also include sending an inverse address resolution
protocol request upon the addition of a new frame relay router. The
interworking function device can provide a transparent proxy
between the Ethernet router and the frame relay router.
In another aspect a computer program product, is tangibly embodied
in an information carrier, for executing instructions on a
processor. The computer program product is operable to cause a
machine to generate a unique media access control (MAC) address for
a frame relay router connected to an Ethernet router, associate the
MAC address with the frame relay router, and store the MAC address
in an interworking function device (IWF). The product is also
configured to receive at the IWF device an address resolution
protocol (ARP) request from the Ethernet router and send from the
IWF device to the Ethernet router a response to the ARP request
based on the stored MAC addresses.
Embodiments can include one or more of the following. The method
can include forwarding a packet to a frame relay router from the
Ethernet router based on the response from the interworking
function device. The method can include sending an inverse address
resolution protocol request upon the addition of a new frame relay
router. The interworking function device can provide a transparent
proxy between the Ethernet router and the frame relay router.
In one aspect, the interworking function (IWF) device allows
transparent communication between an Ethernet network and a frame
relay network. The IWF device stores a list of media access control
addresses for each frame relay connection and responds to ARP
requests of the Ethernet network. This allows the Ethernet network
to send packets to systems on the frame relay network without first
encapsulating the packets.
In another aspect, the assignment of "Virtual" MAC address per
ATM/FR virtual connection means that just one Ethernet identifier
(VLAN or Ethernet MPLS Pseudo-wire) is required towards the
Ethernet "Headquarter" for a set of ATM/FR virtual connections.
This translates can provide one or more of the advantages that
follow. This method can allow optimized migration to Ethernet for
certain types of existing ATM/FR VPNs, for example, where the
enterprise customer point router based in the Hub site employs
Group Mode/Point to Multipoint configurations. This also can allow
lower operational expenses for a both service provider and
enterprise customers subscribing to this service. The system can
include increased scalability and stability in the Ethernet portion
of the network.
DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram of a system including Ethernet and frame relay
networks.
FIG. 2 is a diagram of an interworking device and connections to
Ethernet and frame relay networks.
FIG. 3 is a diagram of address resolution protocol requests.
FIG. 4 is a flow chart of a process to send a packet to a system in
the frame relay network.
FIG. 5 is a flow chart of processing after addition of a new frame
relay connection.
DESCRIPTION
Referring to FIG. 1, a network 10 includes an Ethernet based
network 20 and a frame relay based network 30 connected by an
interworking function (IWF) device 24. The Ethernet based network
20 includes, for example, a headquarter site 22 having one or more
Ethernet capable routers that communicate with multiple frame relay
based or asynchronous transfer mode (ATM) based customer end (CE)
routers. The CE routers could be located at various customer end
locations 32, 34, and 36 and included in the frame relay network
30.
The Ethernet routers, for example, the multiple routers included in
the headquarter site 22, communicate using the specified IEEE 802.3
standard. Ethernet is a local area technology with networks
traditionally operating within a close proximity. In an Ethernet
network, devices attach to a common medium that provides a path
along which the signals will travel. This medium can be been
coaxial copper cable, a twisted pair, fiber optic cabling, and the
like. Devices that attach to the common medium are referred to as
stations or nodes. The stations or nodes communicate using short
messages called frames, which are variably sized chunks of
information. The Ethernet protocol specifies a set of rules for
constructing frames. There are explicit minimum and maximum lengths
for frames, and a set of required information that appears in the
frame. Each frame includes, for example, both a destination address
and a source address, which identify the recipient and the sender
of the message. The address uniquely identifies the node and no two
Ethernet devices should have the same address.
The example below is discussed in terms of a Frame Relay network
but the IWF principles also apply for an ATM network.
The frame relay network 30 in system 10 is a type of point-to-point
network based on packet-switching technology. In a High-level Data
Link Control (HDLC) frame relay network, data is sent in HDLC
packets, referred to as "frames". In a frame relay network, all
circuits (e.g., link between user end points) are permanently
assigned and referred to as "permanent virtual circuits". The
circuits are known as virtual because they are not electrical
circuits where there is a direct electrical connection from end to
end. Rather, there is a "logical" connection, or virtual
connection, where the data moves from end-to-end, but without a
direct electrical circuit. In practice, data from a particular host
arrives at the frame relay switch, from the customer equipment,
with a particular destination address. The frame relay switch,
using its internal lookup table, finds the data a physical port
associated with the address and delivers the data to the correct
location.
As described above, the Ethernet Router on customer premises
(building 22) is directly connected to the IWF. Similarly, the
Routers on the frame relay side are directly connected to the IWF.
However, in both cases, in between the device containing the IWF
and the customer locations (either on the Ethernet or FR/ATM side)
one may use different transport services/method to carry to carry
the Ethernet or FR/ATM packets/cells. An example of such a
transport service could be Multi-Protocol Label Switching (MPLS)
services: i.e. "Martini/PWE3" pseudowires.
Referring to FIG. 2, an example of a system 10 including an
Ethernet network 20 and a frame relay network 30 with an IWF device
24 functioning as an interface between the Ethernet network 20 and
frame relay network 30 is shown. The Ethernet network includes a
network 40 connected to a port 42. The IWF device 24 connects port
42 to multiple frame relay ports 56, 58, and 60 for frame relay
networks 62, 64, and 66.
Interfaces from the customer end devices in the frame relay network
30 terminate into the IWF device 24. Each port (e.g., ports 56, 58,
and 60) is assigned a virtual media access control (MAC) address.
MAC addresses are used by Ethernet networks to route packets from
one location to another. The virtual MAC addresses for each device
are stored in a cache 46 in the IWF device 24. For example, network
62 (connected to port 56) is assigned a MAC address 50 of "A3".
Networks 64 and 66 are assigned MAC addresses 52 and 54 of "A1" and
"A5" respectively. Inverse ARP requests towards the FR CPE are used
(as described in FIG. 6.) to learn the IP addresses from the
related CPE Routers which are subsequently mapped to the
corresponding MAC addresses assigned by the system (A1 to A5).
Referring to FIG. 3, the system uses address resolution protocol
(ARP) requests to map Internet Protocol address (IP address) to a
physical machine address that is recognized in the network. The
physical machine address is also known as a Media Access Control or
MAC address. A table, usually called the ARP cache 46, maintains a
mapping between each MAC address and its corresponding IP address.
ARP provides the protocol rules for making the mapping and
providing address conversion in both directions.
Referring to FIG. 4, when the Ethernet network 20 desires to send a
packet to a system in the frame relay network 30, an ARP request 80
is generated 102 and sent 104 to the IWF device 24. The IWF device
24 finds 106 a physical host or MAC address that matches the IP
address by looking up the physical host or MAC address in the ARP
cache 46. The MAC addresses are associated with the frame relay
devices and are stored in cache 46. The IWF 24 device searches the
cache 46 and if an matching entry is found returns 108 the entry.
This entry is based on the virtual MAC addresses available to the
IWF device 24 in cache 46. Since the IWF device 24 responds to the
ARP request 80 in the same manner as a port on the Ethernet would
respond, the Ethernet network 20 communicates with the IWF device
24 and is not aware that the packets are being sent to a frame
relay network 30.
Referring to FIG. 5, upon addition of a new frame relay connection
88, an inverse ARP request 86 is sent 122 from the IWF device 24 to
the new frame relay device. This inverse ARP request 86 identifies
124 the IP address of the remote end (e.g., frame relay connection
88). Upon the addition of the new frame relay connection 88, the
IWF device 24 updates 126 cache 46 to include the assigned MAC
address for the new port.
The device described herein can be implemented in digital
electronic circuitry, in computer hardware, firmware, software, or
in combinations of them. The device described herein can be
implemented as a computer program product, e.g., a computer program
tangibly embodied in an information carrier, e.g., in a
machine-readable storage device or in a propagated signal, for
execution by, or to control the operation of, data processing
apparatus, e.g., a processing device, a computer, or multiple
computers. A computer program can be written in any form of
programming language, including compiled, assembled, or interpreted
languages, and it can be deployed in any form, including as a
stand-alone program or as a module, component, subroutine, or other
unit suitable for use in a computing environment. A computer
program can be deployed to be executed on one computer or on
multiple computers at one site or distributed across multiple sites
and interconnected by a communication network.
A number of embodiments of the invention have been described.
Nevertheless, it will be understood that various modifications may
be made without departing from the spirit and scope of the
invention. Accordingly, other embodiments are within the scope of
the following claims.
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